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Claims  |
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What is claimed is:
1. A method in a communication system for reliably delivering messages from
a terminal to a selective call receiver, the method comprising the steps
of:
(a) the terminal storing messages for transmission to a selective call
receiver, each message comprising address information, a message sequence
identifier, and message data;
(b) the terminal sequentially transmitting the messages over a first
communication medium for reception by the selective call receiver, the
message sequence identifiers transmitted with the messages identifying the
sequence of transmitted messages that include the same address
information;
(c) the selective call receiver receiving at least some of the transmitted
messages, including the message sequence identifiers associated with the
received messages;
(d) the selective call receiver monitoring a time associated with a last
received message to determine when a predetermined amount of time has
expired;
(e) the selective call receiver determining, after expiration of the
predetermined amount of time, that a transmitted message has been missed
when the last received message is out of sequence with other messages
received by the selective call receiver;
(f) the selective call receiver generating, in response to determining that
a transmitted message has been missed, a message reconciliation request
over a second communication medium, the second communication medium being
different from the first communication medium, the message reconciliation
request identifying a predetermined address for the selective call
receiver and any message sequence identifiers included with the received
messages;
(g) the terminal determining whether any messages that were sequentially
transmitted in step (b) were not received by the selective call receiver
by comparing the message sequence identifiers of the stored messages to
the message sequence identifiers identified in the message reconciliation
request as being received, wherein a stored message is determined to have
not been received when the message sequence identifier of a stored message
is not identified as received in the message reconciliation request;
(h) retrieving each stored message that was determined not to have been
received by the selective call receiver in step (g); and
(i) transmitting over the second communication medium at least the message
data of each of the retrieved messages in step (h) for reception by the
selective call receiver for reliably delivering messages to the selective
call receiver.
2. The method of claim 1 further including, subsequent to step (i), the
steps of:
(j) receiving an acknowledgement from the selective call receiver over the
second communication medium in response to step (i), the acknowledgement
affirmatively acknowledging reception by the selective call receiver of at
least the message data of each of the retrieved messages transmitted in
step (i); and
(k) deleting each of the messages stored in step (a) that was acknowledged
as being received by the selective call receiver in step (j).
3. The method of claim 1 further including, subsequent to step (i), the
step of:
(l) repeating steps (a) through (i), wherein the received message
reconciliation request in step (f) identifies messages received by the
selective call receiver since a previous message reconciliation request
was received identifying the predetermined address for the selective call
receiver.
4. The method of claim 1 wherein the first communication medium is a ratio
frequency paging channel.
5. The method of claim 4 wherein the second communication medium is a
dial-up telephone line interface using modem communication.
6. The method of claim 4 wherein the second communication medium is a radio
frequency communication channel.
7. An electronic mail communication system comprising:
a paging system for reliably delivering electronic mail messages, the
paging system comprising:
first memory means for storing the electronic mail messages, each
electronic mail message comprising address information, a message sequence
identifier, and message data; and
paging transmitting means for sequentially transmitting the electronic mail
messages to at least one selective call receiver over a paging
communication channel; and
at least one selective call receiver, each selective call receiver
comprising:
paging receiving means for receiving the electronic mail messages
sequentially transmitted over the paging communication channel;
decoding means for matching the address information included with each
received electronic mail messages to a predetermined address;
second memory means for storing at least the message sequence identifier
and the message data for each received electronic mail message including
address information that matched with the predetermined address;
determining means coupled to the second memory means for determining that a
transmitted message including address information matching the
predetermined address was not received by detecting that a message
sequence identifier associated with a received message is out of sequence
with the transmission sequence of other stored messages;
timing means coupled to the determining means for providing timing
information thereto for determining that the transmitted message was not
received after a predetermined time interval subsequent to a last received
message being monitored in the transmission sequence, wherein the
determination that the transmitted message was not received is delayed by
the predetermined time interval for monitoring the transmission sequence
up to the expiration of the predetermined time interval; and
reconciliation request initiating means for initiating a reconciliation
request over a dial-up telephone interface in response to the
determination that a transmitted message has been missed and after
expiration of the predetermined time interval, the reconciliation request
identifying
(a) a predetermined address for the selective call receiver and
(b) any message sequence identifiers included with electronic mail messages
received by the selective call receiver,
wherein the received electronic mail messages identified in the
reconciliation request include address information matching the
predetermined address at the selective call receiver; and
wherein the paging system further comprises:
retrieving means for retrieving from the first memory means the electronic
mail messages identified by the reconciliation request as having not been
received by the selective call receiver; and
reconciled message transmitting means for transmitting over the dial-up
telephone interface at least the message data of each of the retrieved
electronic mail messages in response to the reconciliation request; and
wherein each of the at least one selective call receiver further comprises:
reconciled message receiving means coupled to the reconciliation request
initiating means and the second memory means for receiving at least the
message data of each of the retrieved electronic mail messages transmitted
over the dial-up telephone interface in response to the reconciliation
request, and for providing at least the message data received by the
reconciled message receiving means to the second memory means for reliably
delivering the electronic mail messages from the paging system to the at
least one selective call receiver.
8. The electronic mail communication system of claim 7,
wherein the reconciled message transmitting means comprises modem
transmitting means for transmitting over the dial-up telephone interface
at least the message sequence identifier and the message data of each of
the retrieved electronic mail messages using modem communication, and
wherein the reconciled message receiving means comprises modem receiving
means for receiving at least the message sequence identifier and the
message data of each of the retrieved electronic mail messages transmitted
over the dial-up telephone interface using modem communication.
9. A communication system for reliably delivering messages from a central
terminal to at least one communication receiver, wherein the central
terminal comprises:
memory means for storing messages destined for transmission to at least one
communication receiver;
first message transmitting means coupled to the memory means for
sequentially transmitting the messages and message sequence identifiers
associated with the messages over a first communication medium for
reception by the at least one communication receiver;
second message transmitting means coupled to the first memory means for
transmitting messages missed by the at least one communication receiver
over a second communication medium for reception by the at least one
communication receiver in response to reception of a message
reconciliation request generated and transmitted by the at least one
communication receiver, wherein the message reconciliation request
identifies message sequence identifiers associated with messages that have
been received by the at least one communication receiver such that missed
messages can be identified by the central terminal; and
wherein the at least one communication receiver comprises:
receiving means for receiving at least some of the messages transmitted
over the first communication medium;
monitoring means coupled to the receiving means for monitoring the message
sequence identifiers associated with the received messages;
determining means coupled to the monitoring means for determining that a
message transmitted over the first communication medium was not received
by detecting that a message sequence identifier associated with a received
message is out of sequence with the transmission sequence of other
received messages;
timing means coupled to the determining means for providing timing
information thereto for determining that the transmitted message was not
received after a predetermined time interval subsequent to a last received
message being monitored in the transmission sequence, wherein the
determination that the transmitted message was not received is delayed by
the predetermined time interval for monitoring the transmission sequence
up to the expiration of the predetermined time; and
reconciliation request means coupled to the determining means for
generating a reconciliation request over the second communication medium
in response to the determining means determining that the received message
is out of sequence with the transmission sequence of the other received
messages after expiration of the predetermined time interval.
10. The communication system of claim 9 wherein the second communication
medium is a dial-up telephone line interface using modem communication.
11. The communication system of claim 9 wherein the second communication
medium is a ratio frequency communication channel.
12. A portable selective call receiver operable in cooperation with a
communication system for reliably delivering messages from the
communication system to the portable selective call receiver, the portable
selective call receiver comprising:
first receiving means for receiving messages transmitted over a first
communication medium, each transmitted message comprising address
information, a message sequence identifier, and message data, the message
sequence identifiers of transmitted messages identifying a transmission
sequence of the transmitted messages that include the same address
information;
memory means coupled to the first receiving means for storing the received
messages;
decoding means for matching the address information of a received message
to a predetermined address;
received message sequence monitoring means coupled to the receiving means
and the decoding means for monitoring the transmission sequence of
received messages that include address information matching the
predetermined address;
missed message determining means coupled to the received message sequence
monitoring means for determining that a transmitted message including
address information matching the predetermined address was not received by
the portable selective call receiver by detecting at least one received
message having a message sequence identifier that is out of sequence with
the transmission sequence of received messages including address
information matching the predetermined address;
message error detecting means coupled to the receiving means and the
decoding means for detecting errors in the message data of a received
message having address information that matches the predetermined address;
message reconciliation requesting means coupled to the missed message
determining means and the message error detecting means for transmitting a
message reconciliation request to the communication system over a second
communication medium for identifying at least one transmitted message that
the portable selective call receiver failed to receive over the first
communication medium, the message reconciliation request identifying the
predetermined address and at least one message sequence identifier, each
of the at least one message sequence identifier corresponding to a
transmitting message that was not received, as determined by the missed
message determining means, or corresponding to a received message having
error in the message data, as detected by the error detection means;
reconciled message receiving means coupled to the message reconciliation
requesting means and responsive thereto for receiving at least the message
data of each of the at least one message corresponding to each of the at
least one message sequence identifier identified in the message
reconciliation request, the reconciled message receiving means receiving
at least the message data of each of the at least one message over the
second communication medium for reliably delivering messages from the
communication system to the portable selective call receiver; and
timing means coupled to the received message sequence monitoring means and
the missed message determining means for providing timing information
thereto for determining that a transmitted message including address
information matching the predetermined address was not received by the
portable selective call receiver after a predetermined time interval
subsequent to a last received message being monitored in the transmission
sequence, the determination that the transmitted message including address
information matching predetermined address was not received being delayed
by the predetermined time interval for monitoring the transmission
sequence up to the expiration of the predetermined time interval.
13. The portable selective call receiver of claim 12, further comprising;
display means coupled to the message reconciliation requesting means for
visually indicating to a user that the portable selective call receiver
failed to receive at least one transmitted message over the first
communication medium; and
user input control means coupled to the message reconciliation requesting
means for receiving user input including a user confirmation of the visual
indication that the portable selective call receiver failed to receive at
least one transmitted message, the received user confirmation being
coupled to the message reconciliation requesting means for transmitting
the message reconciliation request to the communication system in response
to receiving the user confirmation.
14. The portable selective call receiver of claim 12, wherein the first
communication medium is a radio frequency paging communication channel,
and wherein the second communication medium is one of the set of
communication media including a dial-up telephone line interface using
modem communication and a radio frequency communication channel.
15. The portable selective call receiver of claim 12, wherein each of the
messages transmitted over the first communication medium includes a cyclic
redundancy code (CRC) for detecting at least one error in the message
data, and wherein the message error detecting means utilizes the CRC of a
received message having address information that matches the predetermined
address for detecting error in the message data of the received message. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates generally to message communication systems, such as
for electronic mail systems, and more specifically to a method and
apparatus for reliably delivering messages to one or more remote units
from a central communication system utilizing a paging transmitter system.
BACKGROUND OF THE INVENTION
Communication systems, such as paging systems, typically communicate
messages from an originating device to one or more destination devices.
These messages can include numeric and alphanumeric information for a user
of the destination device. The destination device, e.g., a selective call
receiver or pager, typically presents the information received to the user
by displaying the information on a display.
Contemporary paging systems offer a limited message length for
communicating information. For example, an alphanumeric message may be
typically 80 characters or less. These typical message lengths have
provided reasonably reliable delivery of messages to the users of the
communication system.
On the other hand, a distinct trend in the market is for customers desiring
much longer messages, such as messages that are ten to one hundred times
longer or more. Transmission of these messages over a paging channel can
encounter a number of obstacles to reliable delivery of the longer
messages, such as different types of interference, fading, noise, and
other phenomena detracting from error-free and reliable communication of
the messages to the destination devices.
This difficulty in reliable transmission of the longer messages is
especially frustrating to customers that are used to communicating long
messages over a more reliable communication medium, such as direct wire
line or dial-up telephone communication. This is particularly the case for
electronic mail system users which typically desire to send relatively
long messages with a high degree of certainty that the messages are
received error free. Typically, an originating device, such as a personal
computer or workstation, can send long messages to one or more destination
devices, such as other personal computers or workstations, over a direct
wire line interface, or over a local area network (LAN), or over a dial-up
telephone line connection using the public switched telephone network
(PSTN).
Therefore, a need exists to enhance the reliability of transmitting
messages, including long messages, in communication systems that utilize
paging systems for delivering the messages.
SUMMARY OF THE INVENTION
A method in a communication system for reliably delivering messages from a
terminal to a selective call receiver comprises the steps of the terminal
storing messages for transmission to a selective call receiver, each
message comprising address information, a message sequence identifier, and
message data and then sequentially transmitting the messages over a first
communication medium for reception by the selective call receiver, wherein
the message sequence identifiers are transmitted with the messages to
identify the sequence of transmitted messages that include the same
address information. The selective call receiver receives at least some of
the transmitted messages, including the message sequence identifiers
associated with the received messages, monitors a time associated with a
last received message to determine when a predetermined amount of time has
expired, and determines, after expiration of the predetermined amount of
time, that a transmitted message has been missed when the last received
message is out of sequence with other messages received by the selective
call receiver. The selective call receiver generates, in response to
determining that a transmitted message has been missed, a message
reconciliation request over a second communication medium that is
different from the first communication medium. The message reconciliation
request identifies a predetermined address for the selective call receiver
and any message sequence identifiers included with the received messages.
The terminal then determines whether any of the sequentially transmitted
messages were not received by the selective call receiver by comparing the
message sequence identifiers of the stored messages to the message
sequence identifiers identified in the message reconciliation request as
being received, wherein a stored message is determined to have not been
received when the message sequence identifier of a stored message is not
identified as received in the message reconciliation request. The terminal
retrieves each stored message that was determined not to have been
received by the selective call receiver and transmits over the second
communication medium at least the message data of each of the retrieved
messages for reception by the selective call receiver for reliably
delivering messages to the selective call receiver.
An electronic mail communication system comprises a paging system for
reliably delivering electronic mail messages. The paging system includes
first memory means for storing the electronic mail messages, each
electronic mail message comprising address information, a message sequence
identifier, and message data. The paging system further includes paging
transmitting means for sequentially transmitting the electronic mail
messages to at least one selective call receiver over a paging
communication channel and at least one selective call receiver. Each
selective call receiver comprises paging receiving means for receiving the
electronic mail messages sequentially transmitted over the paging
communication channel and decoding means for matching the address
information included with each received electronic mail message to a
predetermined address. Second memory means stores at least the message
sequence identifier and the message data for each received electronic mail
message including address information that matched with the predetermined
address, and determining means coupled to the second memory means
determines that a transmitted message including address information
matching the predetermined address was not received by detecting that a
message sequence identifier associated with a received message is out of
sequence with the transmission sequence of other stored messages. Timing
means coupled to the determining means provides timing information thereto
for determining that the transmitted message was not received after a
predetermined time interval subsequent to a last received message being
monitored in the transmission sequence, wherein the determination that the
transmitted message was not received is delayed by the predetermined time
interval for monitoring the transmission sequence up to the expiration of
the predetermined time interval. Each selective call receiver also
includes reconciliation request initiating means for initiating a
reconciliation request over a dial-up telephone interface in response to
the determination that a transmitted message has been missed and after
expiration of the predetermined time interval. The reconciliation request
identifies a predetermined address for the selective call receiver and any
message sequence identifiers included with electronic mail messages
received by the selective call receiver, wherein the received electronic
mail messages identified in the reconciliation request include address
information matching the predetermined address at the selective call
receiver. The paging system further comprises retrieving means for
retrieving from the first memory means the electronic mail messages
identified by the reconciliation request as having not been received by
the selective call receiver and reconciled message transmitting means for
transmitting over the dial-up telephone interface at least the message
data of each of the retrieved electronic mail messages in response to the
reconciliation request. Each of the at least one selective call receiver
further comprises reconciled message receiving means coupled to the
reconciliation request initiating means and the second memory means for
receiving at least the message data of each of the retrieved electronic
mail messages transmitted over the dial-up telephone interface in response
to the reconciliation request, and for providing at least the message data
received by the reconciled message receiving means to the second memory
means for reliably delivering the electronic mail messages from the paging
system to the at least selective call receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a communication system in accordance with the
preferred embodiment of the present invention.
FIG. 2 is a message block diagram illustrating a transmitted message
according to the preferred embodiment of the present invention.
FIG. 3 is a message sequence diagram illustrating a first example of
received messages being stored in the memory of a remote unit of the
communication system according to the preferred embodiment of the present
invention.
FIG. 4 is a message sequence diagram illustrating a second example of
received messages being stored in the memory of a remote unit of the
communication system according to the preferred embodiment of the present
invention.
FIG. 5 is a block diagram illustrating messages stored in the memory of a
central terminal of the communication system and messages stored in the
memory of a remote unit before a reconciliation of messages between the
central terminal and the remote unit, in accordance with the preferred
embodiment of the present invention.
FIG. 6 is a flow diagram illustrating an operational sequence for a remote
unit, according to the preferred embodiment of the present invention.
FIGS. 7 and 8 are message sequence diagrams illustrating a timing aspect of
the second example of FIG. 4, in accordance with the preferred embodiment
of the present invention.
FIGS. 9 and 10 are flow diagrams illustrating operational sequences for the
central terminal of FIG. 1, according to the preferred embodiment of the
present invention.
FIGS. 11 and 12 are flow diagrams illustrating operational sequences for
the remote unit of FIG. 1, according to the preferred embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a communication system 100 utilizing a paging transmitter
system 120, 122, 124, 126, for delivering messages to at least one
portable remote unit, e.g., a portable selective call receiver 130, in
accordance with the preferred embodiment of the present invention. A
central terminal 102 comprises input sections 110, 112 for receiving
inputs from a number of different devices 104, 106, 108, including
receiving page requests for initiating pages that are transmitted by the
paging transmitter system 120, 122, 124, 126, to the at least one portable
remote unit 130. The central terminal 102 has input sections 110 that
interface with the telephone company equipment, such as the public
switched telephone network (PSTN) 107. Personal computers or other
computing devices 104 can access the input sections 110 through the PSTN
using a dial-up telephone line and modem communication. Other calling
devices, such as telephone input devices 106 can access the input sections
110 of the central terminal 102 through the PSTN. Typically, these input
devices 104, 106, can remotely initiate page requests through the central
terminal 102 by calling up the input sections 110 of the central terminal
102 over dial-up telephone lines of the PSTN 107.
Alternatively, other input sections 112 of the central terminal 102 can
receive inputs, such as page requests, from local computing devices 108,
such as a local personal computer or console or other terminal device.
Typically, the one or more local input devices 108 interface with the
input sections 112 of the central terminal 102 via direct wire line
connections using standard RS-232 or RS-422 interface.
The input sections 110, 112, communicate page requests to a controller 114
through a communication bus 116. The controller 114 may comprise
controller circuitry and associated memory such that an incoming page
request may be accepted and stored into available memory for subsequent
transmission to one or more selective call receivers 130. Additionally, a
non-volatile memory device 118, such as battery backed up RAM, one or more
disc drive units, or other non-volatile storage medium, is utilized by the
controller 114 for longer term storage of messages destined for the one or
more selective call receivers 130. The controller 114 typically couples
the message information and other associated information to the memory
device 118 via the bus 116. The message information, which can include
numeric, alphanumeric, or binary information, and other associated
information stored in the memory 118 can be used by the controller 114 for
reliable delivery of the message to the destination or remote unit 130, as
will be more fully discussed below.
The controller 114 couples messages to the paging encoder 120 over the bus
116 for encoding the messages for transmission over a paging channel. The
paging encoder 120 then couples the encoded messages over a communication
path 122 to one or more paging transmitter systems 124, 126, for
transmission over a paging communication channel. The communication path
122, in this example, will be labeled path B which routes the messages
from the central terminal 102 to a paging transmitter system 124, 126, and
over a paging communication channel for reception by the one or more
selective call receivers 130. The general operation of a communication
system including a paging system of the type shown in FIG. 1 is more fully
described in U.S. Pat. No. 5,138,311, issued Aug. 11, 1992, entitled,
"Communication System Having Adaptable Message Information Formats", which
is assigned to the same assignee as the present invention and is
incorporated herein by reference. The selective call receiver 130
preferably incorporates a paging receiver 134 that operates to receive
messages transmitted over the paging communication channel through the
antenna 132. The operation of a paging receiver 134 of the general type
shown in FIG. 1 is well known and is more fully described in U.S. Pat. No.
4,518,961 issued May 21, 1985, entitled, "Universal Paging Device With
Power Conservation", which is assigned to the same assignee as the present
invention and is incorporated herein by reference.
The paging receiver 134 couples a received message to the controller 136
through the bus 138. The controller 136 operates to decode the received
message, for matching address information in the received message to a
predetermined address in the selective call receiver 130. In this way, the
controller 136 can determine whether the received message is intended for
the particular selective call receiver 130. Further, a memory 140 is
coupled to the paging receiver 134 and the controller 136 through the bus
138 for storing the received message in the memory 140. A user can access
user input means 141, such as buttons or switches, at the remote unit 130
to cause the message data of a received message to be displayed on a
display, e.g., a liquid crystal display (not shown). The user can then
read the message that is visible on the display. User input at the remote
unit 130 can also cause the remote unit 130 to perform other functions
known to users of selective call receivers and portable personal computing
devices.
A real time clock 142 is also coupled through the bus 138 to the controller
136 for providing time information thereto. The remote unit 130 is then
capable of providing time information to the user as part of displaying
information on the display (not shown). Additionally, the controller 136
can utilize the time information provided by the real time clock 142 to
keep track of the time when messages were received at the remote unit 130,
and other useful operations that will be more fully discussed below.
Furthermore, the selective call receiver 130 includes a modem transmitting
unit and a modem receiving unit 144 and the associated telephone
interfacing circuitry or other suitable communications apparatus (e.g.
packet radio modem) which allows the user of the selective call receiver
130 to connect the selective call receiver 130 to a telephone interface
150, such as may be provided by an RJ11 plug 148 and associated wiring 146
at the selective call receiver 130 and the complimentary wall jack 150 and
associated wiring 152 thereof. This telephone interface 144, 146, 148,
150, 152, allows the controller 136 of the selective call receiver 130 to
remotely access the central terminal 102 through a dial-up telephone line
and the PSTN 107. At the central terminal 102, a modem transmitting unit
and a modem receiving unit 111 is capable of communicating with the modem
144 at the selective call receiver 130. In this way, the selective call
receiver 130 can communicate with the central terminal 102 and receive
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